The present invention is directed to an electromagnetic system for obtaining motion along two orthogonal axes, and more particularly to two-axis motion of take-out tongs in an individual section glassware forming machine.
An individual section glassware forming machine conventionally comprises a plurality of individual sections disposed adjacent to each other in a line parallel to a machine conveyor. Each machine section includes one or more blank molds for forming parisons from gobs of molten glass, one or more blow molds for blowing the parisons into articles of glassware, a sweepout station (sometimes referred to as a pushout station) for transferring articles of glassware onto the machine conveyor, and take-out tongs for transferring the articles of glassware from the blow molds to the sweepout station. The individual sections operated independently of each other but in synchronism at a defined phase relationship to each other corresponding to the so-called firing order of the machine. An individual section machine of this character is disclosed, for example, in U.S. No. Pat. 4,427,431.
The take-out tongs of a glassware forming machine section must move in two axes, vertically to remove the articles of glassware from the blow molds and deposit the glassware on the dead plate of a sweepout station, and laterally (either linearly or rotationally) between the blow molds and the dead plate. These motions in the past have been obtained pneumatically by means of air actuators, and a multiplicity of air valves coupled to a machine timing shaft or to machine control electronics. Attempts to replace the air actuators with electromagnetic actuators or motors have not been entirely successful in part due to the harsh environmental conditions in which an individual section machine operates, and because of limited space availability. Furthermore, there is a problem associated with motion of electrical conductors. In typical two-axis systems involving two electric motors, the first motor is mounted on a fixed frame and coupled to a movable carriage. The second motor and the operating mechanism (such as take-out tongs) are mounted on the second carriage. The electrical conductors to the second motor thus must move along with the carriages, and numerous solutions have been proposed to protect these conductors from abrasion and damage. Past attempts to employ electric motors have failed because of wire abrasion, and because of vibration at the pick-up tongs.
It is therefore a general object of the present invention to provide a motor-driven two-axis motion control system for controlling motion at the take-out tongs of an individual section glassware forming machine and other like applications. Another and more specific object of the present invention is to provide a two-axis motion system of the described character in which all electrical wiring is stationary, which is particularly well adapted for use in the confined space of an individual section glassware forming machine, in which lubricant is self-contained, leading to enhanced operating lifetime and reduced product contamination, which is particularly well adapted for use in the harsh environment of an individual section glassware forming machine, and which employs rugged and reliable components. A further object of the present invention is to provide a two-axis motion system of the described character in which vibration is reduced or eliminated.
An individual section glassware forming machine in accordance with one aspect of the present invention includes at least one blow mold for forming articles of glassware, a sweepout station for transferring glassware to a machine conveyor, and a take-out mechanism for transferring glassware from the blow mold to the sweepout station. The take-out mechanism comprises first and second electromagnetic stators mounted in fixed position above the blow mold and the sweepout station. A first electromagnetic armature is mounted for linear motion along a first axis (e.g., horizontal) adjacent to the first stator, such that electromagnetic coupling between the first stator and the first armature propels the first armature along the first axis. A second electromagnetic armature is mounted to the first armature for linear motion along a second axis (e.g., vertical) perpendicular to the first axis adjacent to the second stator, such that electromagnetic coupling between the second stator and the second armature propels the second armature along the second axis with respect to the first armature. Take-out tongs are carried by the second armature for engaging and transferring glassware from the blow mold to the sweepout station. The second stator in the preferred embodiment of the invention is disposed in a vertical plane, and has a first dimension corresponding to the motion of the first armature along the first axis and a second dimension perpendicular to the first dimension corresponding to motion of the second armature along the second axis.
The first armature in the preferred embodiment of the invention is mounted on a first carriage for motion along the first axis, and the second armature is mounted on a second carriage carried by the first carriage for motion along the second axis with respect to the first carriage and the first armature. The take-out tongs are suspended from the second carriage. The first and second carriages are movably coupled to the support frame, preferably by tension cables, to reduce or eliminate vibration at the take-out tongs. The armatures comprise respective magnets carried by the associated carriages for motion adjacent and opposed to the associated stators. Each stator preferably comprises a plurality of ferromagnetic laminations coupled to associated stator coils. The stator coils are thus disposed in stationary position surrounding the associated stator laminations, and do not move with the armatures and carriages. Furthermore, the entire two-axis motion system comprises a narrow assembly that can be readily encased for protection against grit and other contaminants in the harsh environment of an individual section machine glassware forming system. Lubricant may be self-contained within the assembly for enhancing the operating life of the assembly.
Although the two-axis motion system of the invention is disclosed in conjunction with, and specifically adapted for use in conjunction with, the take-out tongs of an individual section glassware forming machine, it will be recognized that the system of the invention can be readily employed in other applications. Thus, in accordance with a second aspect of the present invention, a two-axis motion system comprises first and second electromagnetic stators mounted in a first plane, and first and second electromagnetic armatures mounted for motion along respective axes parallel and adjacent to the plane of the armatures. Electrical connection is made using stationary wiring.